In some of conventional fin-and-tube heat exchangers that employ heat transfer tubes of a flat shape (hereinafter referred to as “flat tube”), a recessed portion of each of plate fins, through which the flat tube is inserted, is located on a windward side in a mainstream direction of airflow, and a plurality of elevated portions (louvers) are formed between the adjacent recessed portions (see, for example, Patent Literature 1). The louvers formed in the fin-and-tube heat exchanger according to Patent Literature 1 are different from each other in length in a vertical direction, transverse width, and pitch in the transverse direction.